1. Field of the Invention
The present invention relates to a manufacturing method for a semiconductor device. More particularly, the present invention relates to a manufacturing method for a pixel structure.
2. Description of the Related Art
Accompanied by the significant progress in video communication technologies, a large number of different display devices have been used as display screens in all sorts of consumer electronic products including mobile phones, notebook computers, digital cameras and personal digital assistants. Today, liquid crystal display (LCD) and organic light-emitting diode (OLED) display have become the two most popular mainstream products among various types of display devices because of their light weight, streamlined body and their low power consumption. The method of manufacturing the liquid crystal display or the organic light-emitting diode (OLED) display includes forming a pixel array on a substrate in a semiconductor process. By adjusting the display color of various pixels in the pixel array, the display device can produce colorful and high-quality pictures.
FIGS. 1A through 1E are schematic cross-sectional views showing the steps for manufacturing a conventional pixel structure. As shown in FIG. 1A, a first photomask 210 is used to form a source 110 and a drain 120 on a substrate 50. Then, as shown in FIG. 1B, a second photomask 220 is used to form a channel layer 130 on the substrate 50 and a portion of the source 110 and the drain 120. As shown in FIG. 1C, a first dielectric layer 140 is formed over the substrate 50 to cover the source 110, the drain 120 and the channel layer 130. Then, using a third mask 230, a gate 150 is formed on the first dielectric layer 140. As shown in FIG. 1D, a second dielectric layer 160 is formed on the first dielectric layer 140 and the gate 150. After that, a fourth photomask 240 is used to form a contact window 170 that exposes a portion of the drain 120 in the first dielectric layer 140 and the second dielectric layer 160. As shown in FIG. 1E, a fifth photomask 250 is used to form a transparent conductive layer 180 over the second dielectric layer 160. A portion of the transparent conductive layer 180 fills the contact window 170 so that the transparent conductive layer 180 is electrically connected to the drain 120. Up to this step, the process of fabricating the pixel structure 100 is completed.
Accordingly, the main cost for producing the pixel structure 100 lies in the fabrication of photomasks. In the conventional technique, five different photomasks are used in the process of manufacturing the pixel structure 100 so that the production cost can hardly be reduced. Furthermore, as the size of the substrate increases to accommodate more devices, a larger size photomask must be deployed to form the pixel structure 100. Ultimately, the cost of producing the pixel structure 100 will increase even further.